In a final step, the received symbols \(\) , residing in the TF domain, are mapped back to the DD domain using the SFFT, defined as [1]}
\([n,k] \triangleq \frac{1}{\sqrt{KL}} \sum _{l=0}^{L-1} \sum _{m=0}^{K-1} e^{-j2\pi \left(\frac{k}{K}m-\frac{n}{L}l\right)},\) 
